DESCRIPTION The purpose of this study is to evaluate the interactions of angiotensin II (Ang II) and arachidonic acid (AA) metabolites in the regulation of ion transport in the medullary thick ascending limb (mTAL) in the rat kidney. This study will investigate Ang II-induced changes in ion transport in the mTAL by correlating them with Ang II-induced release of eicosanoids. This study will also investigate the possible role of tumor necrosis factor (TNF) in response to Ang II.